The present invention relates to ink jet printing systems that make use of replaceable ink cartridges. More particularly, the present invention relates to a replaceable ink cartridge that includes a flexible ink bag of a particular configuration optimized to hold a specific volume of ink while constrained within the ink cartridge housing.
With ink jet printers using a remotely located ink cartridge (off carriage) comes the ability to increase the volume of the ink cartridge without impacting the ability of the print head carriage to perform its function during the printing process. Typically the mass of the carriage supporting the print heads needs to be reduced so as to minimize the inertial load on it during acceleration. The ink is supplied to the print heads using flexible tubing. The ink cartridge is located in an ink cartridge receiver assembly and can be coupled to the flexible tubing via a needle and septum interface. This ink delivery system needs to provide a barrier between the ink and the atmosphere due to the sensitivity of the piezoelectric print head to dissolved or entrained gases in the ink.
In piezoelectric print heads, dissolved gases in the ink can quickly come out of solution during the extreme pressure pulsation created in the drop formation process. These gases can accumulate in the print head nozzle and then, due to its compressibility, prevent the expulsion of the ink to the print media. In addition, large supplies of ink are required to minimize the involvement of the operator when high volume, off carriage ink cartridges are included in the design of the printer.
The off carriage ink cartridge is typically configured with a plastic or cardboard housing and flexible ink bag contained therein. The ink cartridge can be mounted either horizontally or vertically. The flexible ink bag allows the ink to be consumed without exposing it to air or creating a vacuum within the ink cartridge.
One such method of ink containment is the use of a cardboard box loaded with a flexible ink bag. The cartridge is mounted onto the printer in a horizontal fashion and ink removed from it during the printing process.
Another method involves placing a flexible ink bag, as shown in U.S. design Pat. No. D341,157, inside an assemblable plastic ink cartridge housing and attaching it to the inside wall of the housing using double sided tape, as shown in U.S. Pat. No. 5,666,146. On the opposing side of the bag a rigid plastic member is attached using double sided tape. This ink cartridge is loaded onto the machine in a horizontal fashion such that as the ink is removed from the cartridge the pressure level within the bag does not change significantly. This housing is substantially larger than the volume of the ink bag and does not constrict the shape of the ink bag when it is full or when at any level less than full. The tape, the rigid plastic member, and relative stiffness of the flexible bag is suitable to keep it in a shape which evacuates properly. The drawback to this design is the excessive space required by the housing and the horizontal loading direction that limits its usable size.
It is therefore an object of the invention to provide an ink cartridge with an improved structure for supporting ink therein and method of filling the cartridge with ink the novel features of which are set forth in the independent claims appended hereto.
The invention, and its objects and advantages, will become more apparent in the detailed description of the preferred embodiments presented below when read in conjunction with the accompanying drawings.